| With the development of shipping and waterway construction in our country and the development of the application research of geographic spatial data, the information construction of inland waterway, especially the application of geographic spatial data of waterway surveying, has been greatly improved. As the important part of the digital waterway research, the application of spatial information can provide dynamic information about the waterway for the ship users and monitoring departments. So, more efficient and rich waterway spatial data model and the application systems are important for the ship users and monitoring departments.Based on the technology project "Research on the Key Technologies of Multi-dimensional Digital Waterway Basic Platform" of Changjiang Nanjing Waterway Bureau, this thesis focuses on the application research of the spatial information of digital waterway. This thesis mainly studies the spatial data model and its application key technologies of the digital waterway by the theoretical method and engineering application, it mainly finishes seven aspects of the problem. Specific research work is as follows:(1) In order to provide richer spatial information for the digital waterway, this thesis analyzes the multi-dimensional description method of different data types, including sounding information, navigation mark information, overland terrain information, shore building and infrastructure, and so on, designs a multi-dimensional waterway model based on the fusion of two-dimensional and three-dimensional multi-source spatial information.(2) For the problem of three-dimensional spatial description of underwater terrain in the multi-dimensional waterway model design, this thesis proposes a construction method of the multi-resolution underwater terrain. Firstly, a pyramid data model of the overland terrain is constructed and a threshold calculation method for the fusion of terrain data and sounding data is designed. Then, the distance-weighted averaging method is adopted to do the data fusion level by level to fuse the overland terrain data with the sounding data.(3) For the fusion problem of multi-scale waterway chart, remote sensing image, underwater three-dimensional terrain in the multi-dimensional waterway model design, this thesis proposes a multi-scale waterway chart fusion algorithm. In the three-dimensional scene, the specific data fusion process of multi-scale waterway chart data, remote sensing image data and underwater terrain data is studied, including view-dependent visualization of multi-scale waterway chart data, map sheet processing order of waterway chart, map sheet clipping and splice, rendering method of objects in the waterway chart and picking up method of objects.(4) Three-dimensional model can describe much richer spatial information. In order to efficiently and precisely fuse three-dimensional models in the multi-dimensional waterway model, this thesis proposes a three-dimensional model data fusion algorithm which is based on the vector data. Firstly, description method of the three-dimensional model is given, a concept of simple mesh which is used for the projection calculation of the three-dimensional model is defined and a series of basic calculation methods, including intersection test algorithm, general counterclockwise order algorithm, silhouette extraction algorithm, and so on, are designed. Then, the fusion process of three-dimensional model is studied based on the above basic concepts and calculation methods, including pose adjustment, size adjustment and position matching.(5) For the current application habit of waterway spatial data, Mercator transformation of multi-dimensional waterway model is constructed to transform the multi-dimensional waterway model between spherical coordinates and Mercator projection scene coordinates and the transformation method is analyzed.(6) Based on the design of the multi-dimensional waterway model, the function structure and the system architecture of multi-dimensional waterway basic platform are designed by referencing the two-dimensional electronic waterway chart system, three-dimensional digital earth system and digital waterway related service systems. And rendering related methods of multi-dimensional waterway model are studied, including multi-layer technology of data fusion, view-dependent LOD visualization technology, asynchronous multi-threaded method, preread strategy of data dispatching, model transformation and hiding method based on the viewpoint and view angle, and so on. The multi-dimensional waterway basic platform is constructed.(7) The multi-dimensional waterway basic platform is applied to the ship navigation and waterway monitoring. For the demands of rendering and information query of dynamic targets in the multi-dimensional waterway model, this thesis proposes a binary thinning method, a level of detail rendering method and a picking up method based on the thought of ray tracing. Multi-dimensional waterway monitoring system is designed and developed. This system implements navigation mark monitoring, water level monitoring, ship monitoring based on the multi-dimensional waterway model. Multi-dimensional ship navigation system is designed and developed. This system implements the ship navigation function based on the multi-dimensional waterway model.Based on the above researches, this thesis provides a new spatial data organization model for the digital waterway and proves the validity of this model in the application research. |
